1. Technical Field
The present disclosure relates to a vibration damping device. More specifically, the present disclosure relates to a vibration damping device for an automobile, which is used for an engine mount of the automobile, and the like.
2. Related Art
The following description sets forth the inventor's knowledge of related art and problems therein and should not be construed as an admission of knowledge in the prior art.
In the related art, automobiles, rail vehicles, and the like are respectively provided with a various types of vibration damping devices to prevent vibration or impact from being transferred to stiff components. For the vibration damping devices, a large number of devices made of metal/rubber composites have been studied and developed and have been used in practice. Such devices have been formed by bonding vulcanized rubber to a metal-made support member. Recently, vibration damping devices made of resin/rubber composites have been widely used as those for automobiles, especially as engine mounts thereof, to reduce the weight and manufacturing cost of the vibration damping devices. In the vibration damping devices, a lightweight resin support member (e.g., a resin bracket) made of a resin material is used instead of a traditional metal support member (e.g., a metal bracket).
In the abovementioned vibration damping device made of a resin/rubber composite, among various kinds of resin materials, resin with excellent properties, such as heat resistance and durability, is particularly selected and used as the resin for the lightweight resin support member (e.g., the resin bracket). Presently, the use of a polyamide resin as the material for the resin support member has been regarded as effective (see, for example, Japanese Patent Application Laid-Open No. 2003-214494). The reasons therefor include that polyamide resin is superior in properties of reinforcement with glass fibers, mold-injection properties during processing, and chemical resistant properties and that the manufacturing cost of the vibration damping device can be lowered by using a polyamide resin, and the like.